Dup= 72 miles
<span>ddown= 120 miles </span>
<span>v= riverspeed </span>
<span>rup= 32mph - v </span>
<span>rdown= 32mph + v </span>
<span>t both ways= t </span>
<span>d=r*t </span>
<span>d/r=t </span>
<span>t=ddown/rdown </span>
<span>t=dup/rup </span>
<span>dup/rup = ddown/rdown </span>
<span>(72)/(32-v)=(120)/(32+v) </span>
<span>3840-120v=2304+72v </span>
<span>1536=192v </span>
<span>v=8</span>
if we take 30 to be the 100%, what is 27 off of it in percentage?
![\begin{array}{ccll} amount&\%\\ \cline{1-2} 30 & 100\\ 27& x \end{array} \implies \cfrac{30}{27}=\cfrac{100}{x} \\\\\\ \cfrac{10}{9}=\cfrac{100}{x}\implies 10x=900\implies x=\cfrac{900}{10}\implies x=90](https://tex.z-dn.net/?f=%5Cbegin%7Barray%7D%7Bccll%7D%20amount%26%5C%25%5C%5C%20%5Ccline%7B1-2%7D%2030%20%26%20100%5C%5C%2027%26%20x%20%5Cend%7Barray%7D%20%5Cimplies%20%5Ccfrac%7B30%7D%7B27%7D%3D%5Ccfrac%7B100%7D%7Bx%7D%20%5C%5C%5C%5C%5C%5C%20%5Ccfrac%7B10%7D%7B9%7D%3D%5Ccfrac%7B100%7D%7Bx%7D%5Cimplies%2010x%3D900%5Cimplies%20x%3D%5Ccfrac%7B900%7D%7B10%7D%5Cimplies%20x%3D90)
Answer:
Choice 3 and 5
Step-by-step explanation: